The present invention relates to an apparatus for detecting a 3D structure of an object comprising at least three laser emitters, optical devices, a detector and an analysis unit.
Laser emitters each generate laser radiation with a wavelength in such a manner that the wavelengths of the emitted laser radiation differ from one another. At least two of the laser emitters emit laser radiation in the invisible range. At least one of the optical devices is a beam splitter, which splits the laser radiation of the laser emitters into a reference radiation and an illumination radiation in such a manner that the illumination radiation strikes the object to be measured, is reflected by the object as object radiation and interferes with the reference radiation. The detector receives the interference pattern formed due to the interference of the reference radiation and the object radiation. The analysis unit is connected to the detector and serves to analyze the interference pattern received. The analysis unit is designed to detect the object in three dimensions based on the interference patterns of the invisible laser radiation.
Such apparatuses are used in dentistry, for example. They are used to detect objects such as a tooth, parts of a jaw or a complete jawbone in three dimensions. The dimensions required for producing models of the bite and the jaw can thus be detected without contact. This completely eliminates the task of taking impressions directly on the patient.
EP 2796938 discloses such an apparatus. It operates according to the principle of digital holography. The apparatus comprises at least two laser emitters, which emit laser radiation at different wavelengths. The laser radiation of each laser emitter is divided into reference radiation and object radiation with the help of a beam splitter. Whereas the reference radiation is deflected to a detector by means of a mirror arrangement, the illumination radiation strikes the object to be detected, is reflected by it as object radiation and is also sent to the detector. The reference radiation and object radiation with an identical wavelength interfere with one another. The resulting reference patterns are received by the detector. The three-dimensional structure of the object to be measured can be detected on the basis of interference patterns formed by laser radiation from different laser emitters. However, the color of the object cannot be detected because light from the near-infrared range is preferably used.